Basics of Vehicle Truck and Suspension
Systems and Fundamentals of Vehicle
Steering and Stability
Ralph Schorr, PE
Senior Product Development Engineer
Vehicle/Truck Dynamicist
1
Course Agenda
• Truck Nomenclature
• Wheel/rail influences
• Truck Dynamics
– Physics
• Truck Types
• AAR M‐976
• Truck Maintenance
2
Truck Nomenclature (Bogie)
3-piece truck
Sideframe
Friction Wedge or Shoe
Wheel
Adapter
Spring Group
Adapter Pad
CCSB
Bolster
Control Springs
Load Springs
Axle
Bearing
3
Truck Nomenclature
Brake Beam Guide
Pedestal Roof
Column Wear Plate
Thrust Lugs
Center Bowl
Side Bearing Pad
Bolster/Friction
Pocket
Brake Rod Openings
Gibs
4
Suspension
Nomenclature
Friction Wedge or Shoe
Bolster
Column Wear Plate
Pocket Wear Plate
Load Springs
Control Springs
Side Frame
5
North American Freight Car
Systems
Capacity
Tons
GRL
Lbs.
Bearing
Size
Wheel Diameter
Inches
70
220,000
Class E
33
100
263,000
Class F
36
110
286,000
Class K
36
125
315,000
Class G
38
6
Contact Patch area
Comparison of Wheel/Rail contact area of
AAR-1B-WF
200
180
160
140
loaded 286k (32.4mt)
Area in mm^2
120
100
80
loaded 263k (29.8mt)
60
40
empty 40k(6.8mt)
20
0
-50
0
50
Lateral position in mm
7
Dynamic Influences
•
•
•
•
•
•
•
Speed
Wheel to Rail Contact
Track Input
Mass/Inertias (Car Body, Truck Components)
Friction
Spring Suspension
Suspension Dampening
8
Multimode Dynamics Software
9
Critical Attributes of the Wheel/Rail
1. Wheel set back‐to‐back dimension
2. Wheel Profile of both wheels
3. Wheel tapeline of both wheels
4. Rail Gauge (I.E. gauge point)
5. Rail Profile of both rails
6. Rail cant or inward tilt of each rail
10
10
Why do wheels have Conicity?
1:12 taper 1:6 taper
cylinder
EC = 0.083
EC = 0
EC = 0.167
*Curtis Urbin of TTCI
11
Wheels conicity in service
• Transit cars = 1:40
• Freight cars = 1:20
12
12
Conicity and Rolling Radius
• Slope angle at point of contact
• Rolling Radius Difference
EC = 0.050
Contact angle = 2.85°
• Effect of Wear on rail and wheel
AAR‐1B‐WF on AREMA A136 railhead
13
13
Hertzian Contact Patch ‐ Creep theory
AAR‐1B‐WF
on new 136# rail
4mm hollow wheel
on TTCI ttt track
Contact Patch Issues:
Steering Force
Lateral Force
* Creep theory
14
Contact Patch in curves
TPD rail profile with “average” worn wheel
Angle of high rail
contact = 6.65°
RRD = ‐0.11 mm
Low rail profile
High rail profile
Low rail profile
High rail profile
Angle of high rail
contact = 42.26 °
RRD = 10.74 mm
15
Wheelset instability
16
16
Truck Hunting
•High Speed
•Typically worse for empty cars
•Rail friction (~ 8 mph)
•Causes wheel wear and lading damage
•Measured in lateral gs rms (0.13gs)
17
Truck Performance Modes
Yaw & Sway
Car / Suspension Specific
Twist & Roll
15-25, 50-60 mph
Pitch & Bounce
50-70 mph
Truck Hunting
Truck Warp, Truck Rotation, Wheelset Movement
40+ mph
18
Carbody Interaction Details
Characteristic
Truck Spacing
Center of Gravity
Predominate Influence
Pitch / Bounce
Twist / Roll
Spiral
Stiffness
Hunting
Inertia
Hunting
Curving
Light Weight
19
Hopper Car on Pitch and Bounce track
F 1 Body leading end v ertic al ac c elerationF 1 Body trailing end v ertic al ac c eleration F 2 Body c .g. v ertic al ac c eleration
F 1 Body c .g. v ertic al ac c eleration
F 2 Body leading end v ertic al ac c elerationF 2 Body trailing end v ertic al ac c eleration
.5
Body leading end vertical acceleration (g's)
.4
.3
.2
.1
0
-.1
-.2
-.3
-.4
-.5
-.6
900
950
1000
1050 1100 1150 1200 1250
Distance along the Track (feet)
1300
1350
20
20
Empty 286k Grain car on Twist and Roll track
Wheel load percent (%) of static
100
90
80
axle 1
70
axle 1
60
axle 2
50
axle 2
40
axle 3
30
axle 3
20
axle 4
10
axle 4
0
0
20
40
Speed in mph
60
80
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21
Truck Interaction Details
Hunting
Curving / Rolling Resistance
Shoe Width
Twist / Roll
Yaw / Sway
Shoe Force
Warp Stiffness
The warp stiffness design is controlled by
the shoe width and force
22
Carbody / Truck Interaction Details
Hunting
Curving / Rolling Resistance
Twist / Roll
Yaw / Sway
Carbody Bolster Interface
Side Bearing / Center Plate friction design
accommodates these regimes and must remain
consistent
23
Truck Interaction Details
KZ
Hunting
KY
KX
Curving / Rolling Resistance
KRAD
Twist / Roll
Passive Steering
•Provides wheelset alignment to reduce
rolling resistance
•Designed stiffness enhances performance
for these regimes
Yaw / Sway
24
Truck Interaction Details
•Friction Shoe
•Springs
Hunting
Friction shoe force limits
warp
Twist / Roll
Tuned friction shoe damping &
suspension stiffness limit Roll
Spiral
Friction shoe force limited to prevent
wheel unloading
Pitch / Bounce
Tuned friction shoe damping &
suspension stiffness limit Pitch /
Bounce
25
Motion Control® Features M-976
Lightweight Castings
Tuned Suspension
36” Class C Wheel
•Stability
•Vert. and Lat. Accelerations
Passive Steering
•Curving
•Rolling Resistance
CCSB
Wide Friction Shoe
•Stability
•Roll Control
•Stability
•Curving
6 ½ x 9 Class K
Roller Bearing
Class K Axle
26
M-976 Friction Shoes
 Motion Control® and SSRM
 Ridemaster
 Super Service Ride Control
 S‐2‐HD Split Wedge
 S‐2‐E
27
Shoe Types
ASF Shoe Design (MoCo,SSRC)
37.5° Angle
30” Slope Radii, Shaped Slope
Steel Shoe
ASF
S2HD
Accommodates:
Bolster/Side Frame Rotation
Part Variation ‐ Casting, Shoe
Provides:
Shoe Stability ‐ Roll and Sway
Warp Stiffness ‐ Edge Contact
Smooth Action
Long Suspension Life
Shoe as Wear Component
28
Shoe Types
Pocket Side Wall
Wear Plate
S2HD Shoe Design
• 32° Angle
• Split Wedge
• Iron Shoe
Split Wedge Insert
Split Wedges
29
Suspension Design
Constant
‐ASF Ride Control
‐ASF SSRC
‐ Buckeye XC‐R
‐ Meridian C‐1, Wedge Lock
Variable
‐Motion Control
‐ ASF Ridemaster
‐Swing Motion
‐Barber S‐2‐HD
30
Secondary Truck Suspensions
** Friction Damping ~ F x D
Variable damping
Constant damping
31
31
Damping Advantages
Constant Damping:
• Long Service Life
• Moderate Track Ride
• Light Car Truck Warp
Variable Damping:
•
•
•
•
High C. of G. Approval
Ease of Maintenance
Rough Track Ride
Service Life Varies by Design
32
Hydraulic Damping in suspensions?
Hydraulic damping:
•
•
•
•
Good Performance
High Speed
Service Life?
Maintenance
33
33
Truck Maintenance
Most wedges have
built‐in wear indicators
34
CCSB must be “long travel”
Use these
35
35
Truck Inspection
•
•
•
•
Shoe Rise
Column Wear Plate Bolts
Gibs
Springs
36
Frame Braced truck
• Increases warp
stiffness
• Typically added to
a 3‐piece truck
37
37
Swing Motion® truck
Pedestal Rocker
Rocker Seat
Transom
38
38
Summary
• Trucks operate as part of an overall system
• Utilize primary and secondary suspensions
• Dynamic performance is dependent on the
assembled suspension parts
• Good maintenance is critical to continued
performance and overall life of the system
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39
Thank You ‐ Questions
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